Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 36)

24 ServerIron ADX Global Server Load Balancing Guide
53-1002437-01
Proxy for DNS server
1
Syntax: host-info <host-name> http | <TCP-portnum> status-code <range> [<range> [<range>
[<range>]]]
You can specify up to four ranges (total of eight values). To specify a single message code for a
range, enter the code twice. For example to specify 200 only, enter the following command: port
http status-code 200 200.
NOTE
When you change the status code ranges, the defaults are removed. As a result, you must specify
all the valid ranges, even if a range also is within the default ranges. For example, if you still want
codes 200-299 to be valid, you must specify them.
NOTE
When a URL string is associated with a TCP port number rather than the well-known HTTP port, the
ServerIron ADX performs both a TCP and an HTTP health check. In this case, you must specify the
method and URL before specifying the status code ranges. The software displays an error message
if you accidentally try to change the status codes before specifying the method and URL.
Configuring DNS domain name aliases
You can configure an alias for a domain name and application configured on the GSLB ServerIron
ADX. This feature is useful together with the DNS cache proxy feature when you want the GSLB
ServerIron ADX to learn a set of proxy server IP addresses for a domain, then respond to client
requests with the best proxy server address.
Typically, you use this set of features when the DNS server contains a single server address for the
actual domain name, but a separate set of proxy server addresses for an alias for that domain
name. When you enable DNS cache proxy and configure the alias for the domain on the GSLB
ServerIron ADX, the GSLB ServerIron ADX:
• Learns the proxy server addresses under the alias on the DNS server instead of the address for
the domain’s actual site. This requires configuration of the alias on the GSLB ServerIron ADX.
• Responds to client queries for the actual domain name with the best site address from among
the proxy server addresses learned from the DNS server under the alias. This requires that
enable the DNS cache proxy feature.
NOTE
Use this feature only in conjunction with the DNS cache proxy feature. Otherwise, it is possible for
the IP address(es) the ServerIron ADX learns under the real domain name and the addresses it
learns under the alias to be different. When this is the case, the ServerIron ADX does not make any
alterations to the DNS response but instead sends the response back to the client unaltered. As a
result, the ServerIron ADX sends the client the DNS reply with the real domain name’s server
address, instead of one of the proxy addresses configured on the DNS server under the domain’s
alias.
To configure an alias for a domain name, enter the alias after entering the zone name and host
application names, as in the following:
ServerIronADX(config)# gslb dns zone brocade.com

ServerIronADX(config-gslb-dns-brocade.com)# host www http

ServerIronADX(config-gslb-dns-brocade.com)# host www alias www.gslb.brocade.com
The commands configure a zone called “brocade.com”, associate an HTTP host named “www” with
the zone, then associate the alias “www.gslb.brocade.com” with the host and zone.